Monday, May 1, 2023

ADRENAL GLAND

DR.NILESH KATE. M.D.

ASSOCIATE PROFESSOR,DEPARTMENT OF PHYSIOLOGY,

OBJECTIVES Physiological anatomy Development. Functional layers.

Macro Micro

Zones Hormones Biosynthesis of steroid hormones. Glucocorticoids normal levels. Transport & metabolism. Mechanism of action of steroid.

INTRODUCTION Among most

important and vital endocrine organ.

Small bilateral yellowish retroperitoneal organ.

Lies just above kidney in gerota’s fascia.

PHYSIOLOGICAL ANATOMY

Right adrenal is triangular, related to upper pole Right kidney

Left adrenal is crescent shaped, related to upper and medial part Left kidney

Size : 3 - 6cm long, Weight : 3-5 gm app Width : 2-3 cm

Adrenal gland -- General considerations

Monday, May 1, 2023

Cortex – 80 to 90 % of gland

Secretes cortisol hormones

Medulla – 10 to 20 %

Secretes Catecholamine.

Development. Adrenal cortex –

Mesoderm derivatives. In fetal life – comprises outer Neocortex &

inner Fetal cortex Fetal cortex degenerates & neocortex

enlarges & differentiates into 3 layered adrenal cortex.

Monday, May 1, 2023

Development.(cont…) Adrenal medulla

Neuroectodermal cells Represents enlarged & specialized

sympathetic ganglion. Develops from the neural crest.

Monday, May 1, 2023

FUNCTIONAL ANATOMY. Position.

Above each kidney. Covered by

connective tissue capsule.

2 parts- Outer cortex Inner medulla.

Monday, May 1, 2023

SUPRARENAL GLAND.(MACROSCOPIC)

Monday, May 1, 2023

MICROSCOPIC(HISTOLOGICAL)

Monday, May 1, 2023

Zona glomerulosa (1/5TH)Inverted U shaped

Zona fasiculata (3/5TH)Sinusoids between columns

Zona reticularis (1/5TH)Compactly arranged cords of cells

ADRENAL GLAND

HORMONES OF ADRENAL CORTEX

ZONA GLOMERULOSA –Mineralocorticoids – AldosteroneDeoxycorticosterone

ZONA FASCICULATA – Glucocorticoids – cortisol or hydrocortisoneCorticosterone.

ZONA RETICULARIS –Sex steroids.– androgen Oestrogen & progesterone .

Monday, May 1, 2023

GLUCOCORTICOIDS Characteristics features.

Cortical cells – large smooth ER. High amount of lipids mainly cholesterol in

ester form. Also vitamin C. All hormones steroid hormones. CPPP Ring 17 hydroxy-corticosteroids 17 ketosteroids.

Monday, May 1, 2023

O

HO

CH2OH

C O

OH

CORTISOL MOLECULAR STRUCTURE

Cyclo-Pentano-Perhydro-Phenantherene Ring

BIOSYNTHESIS OF STEROID HORMONES

Monday, May 1, 2023

Synthesis of hormones.

Monday, May 1, 2023

PLASMA LEVELS Diurnal variations –

10 – 25 μg % (avg 14 μg %) Rate of secretions of cortisol

15 mg/day normally 300 – 400 mg/day under stress.

Monday, May 1, 2023

TRANSPORT Cortisol.

Bound form (90%) CBG (α 2) – Glycoprotein called Transcortin. Albumin (10 %)

Free form (10%) Responsible for physiological actions.

Monday, May 1, 2023

Inter relationship between free & bound form

TRANSCORTIN – normal plasma conc. 3 mg%

Binding capacity – 20 μg / dl. Synthesized in liver. Increased by oestrogen - pregnancy. liver cirrhosis , nephrosis & multiple

myeloma.

Monday, May 1, 2023

METABOLISM & EXCRETION. Major pathway – cortisol & cortisone

Conjugated & excreted in urine.

Cortol glucoronide & cortolone glucoronide.

Minor pathway – conversion to 17-ketostroid conjugated to sulphate & excreted in urine,

Monday, May 1, 2023

EXCRETION. In 24 hr urine

0.03 mg – free cortisol 5 mg – tetrahydrocortisol glucoronide &

cortol glucoronide 3 mg -- tetrahydrocortisone glucoronide &

cortolone glucoronide 6 mg – as 17-ketosteroids. 7 mg – unidentified metabolite. TOTAL – 22 mg.

Monday, May 1, 2023

AVERAGE PLASMA LEVELS- (ADRENAL CORTICAL HORMONES)

Hormones PlasmaConcentrationmicro g’/dl

Daily secretion

14.0 10Corticosterone 0.4 3Aldosterone 0.006 0.15Dehydroepian-drosterone 175.0 20.0

(mg)

Cortisol

MECHANISM OF ACTION.

Monday, May 1, 2023

CORTICOADRENAL REGULATION

REGULATION OF SECRETION OF CORTISOL

StressStress

Hypothalamus-CRHHypothalamus-CRH

Ant Pituitary-ACTHAnt Pituitary-ACTH

HH-Portal SystemHH-Portal System

REGULATION OF SECRETION OF CORTISOLHYPOTHALMO-HYPOPHYSEAL PORTAL SYSTEM

CortisolCortisolReleasingReleasingHormoneHormone

ACTHACTH

OBJECTIVES Physiological anatomy Development. Functional layers.

Macro Micro

Zones Hormones Biosynthesis of steroid hormones. Glucocorticoids normal levels. Transport & metabolism. Mechanism of action of steroid.

Thank you THANK YOU